Question

When you add an xml schema to a document like I understand that the xmlns is not actually the location of the xsd file. Is this correct?

• How do you in practice reference an xml file’s schema?
• Is it usually on a web server? That would seem very chatty.
• Is it referenced by relative path?
• Is it not actually referenced in the xml but rather loaded into an xml parser arbitrarily?

Any feedback?

Answer 1

You have a schema with a target namespace and qualified elements (wich means you don’t have to prefix your elements to apply target namespace):

<?xml version="1.0"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
        targetNamespace="http://www.exemple.com/my-namespace-URI"
        xmlns="http://www.exemple.com/my-namespace-URI"
        elementFormDefault="qualified">
    <-- Your schema definition -->
</xs:schema>

You have to include it in your root element. First the xml-schema namespace:

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

(from here the xsi: prefix corresponds to this namespace)

Then reference the schemaLocation attribute

xsi:schemaLocation="http://www.exemple.com/my-namespace-URI my.xsd"

where my.xsd is the location of the XSD file (by default relative to the XML document’s location). You can put a complete URL like

xsi:schemaLocation="http://www.exemple.com/my-namespace-URI http://www.exemple.org/xml/my.xsd"

So that gives your document:

<?xml version="1.0"?>
<doc xmlns="http://www.exemple.com/my-namespace-URI"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:schemaLocation="http://www.exemple.com/my-namespace-URI http://www.exemple.org/xml/my.xsd">
    <!-- Document content -->
</doc>

Note that the XSD file URL is not necessarily related to the namespace URI.